Auto merge of #100740 - Dylan-DPC:rollup-0td6yq4, r=Dylan-DPC

Rollup of 9 pull requests

Successful merges:

 - #99576 (Do not allow `Drop` impl on foreign fundamental types)
 - #100081 (never consider unsafe blocks unused if they would be required with deny(unsafe_op_in_unsafe_fn))
 - #100208 (make NOP dyn casts not require anything about the vtable)
 - #100494 (Cleanup rustdoc themes)
 - #100522 (Only check the `DefId` for the recursion check in MIR inliner.)
 - #100592 (Manually implement Debug for ImportKind.)
 - #100598 (Don't fix builtin index when Where clause is found)
 - #100721 (Add diagnostics lints to `rustc_type_ir` module)
 - #100731 (rustdoc: count deref and non-deref as same set of used methods)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup

Author: bors

compiler/rustc_codegen_cranelift/src/unsize.rs

@@ -29,6 +29,7 @@ pub(crate) fn unsized_info<'tcx>(
             let old_info =
                 old_info.expect("unsized_info: missing old info for trait upcasting coercion");
             if data_a.principal_def_id() == data_b.principal_def_id() {
+                // A NOP cast that doesn't actually change anything, should be allowed even with invalid vtables.
                 return old_info;
             }
 

compiler/rustc_codegen_ssa/src/base.rs

@@ -151,6 +151,7 @@ pub fn unsized_info<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
             let old_info =
                 old_info.expect("unsized_info: missing old info for trait upcasting coercion");
             if data_a.principal_def_id() == data_b.principal_def_id() {
+                // A NOP cast that doesn't actually change anything, should be allowed even with invalid vtables.
                 return old_info;
             }